What Is the Ratio of Water to Plaster of Paris?
To mix plaster of Paris, it is recommended to use two parts plaster of Paris to one part water. This will allow the powder to dissolve nicely and make a paste.
When working with plaster of Paris, it is important to take proper safety precautions to avoid direct contact by wearing a dust mask and gloves. The powder is very lightweight, making it easy to inhale, which could harm the lungs. The eyes should be protected as well, to minimize the risk of getting the powder or mixture in them.
To work with plaster of Paris, pour the water into the mixing container, then slowly and carefully add the plaster of Paris. It is recommended that a sifter be used to reduce the chance for lumps, though a plastic spoon, or similar utensil can be used for the actual mixing. The powder should be added throughout the mixture and not just in one location, according to First Palette. Additionally, the user should wait to fully mix the powder and water together until the powder has covered the top of the water without any air bubbles.